This invention relates to a viewing window for a power tool guard and, in particular, a viewing window which allows an operator to see a moving cutting tool of the power tool.
One of the problems associated with the use of hand-held power tools is properly aligning the cutting tool of the power tool so that the desired cut is achieved. One particular type of power tool that this problem is especially prevalent with is a hand-held circular saw. When using a hand-held circular saw, an operator normally will draw a line on the workpiece indicating the direction and pattern of cut. Circular saws typically have an upper saw guide which encases an upper peripheral portion of the blade. This upper saw guide prevents the operator from seeing whether the blade itself is actually following the marked cut line. Therefore, problems arise when the user initially attempts to align the saw blade with the cut line and further continues as the user attempts to keep the blade tracking upon the cut line.
Attempts have been made in the past to allow the user of a saw to view the blade of the saw through the guide and thus determine if the blade is properly tracking along the desired cut line. One such device is disclosed in U.S. Pat. No. 4,450,627. This patent discloses a circular saw with a clear viewing window on the upper saw guard. The structure disclosed in this patent suffers from various disadvantages. More specifically, the window is disclosed as being made of a transparent plastic material. First, plastic materials typically are susceptible to being electrostatically charged such that dust particles are likely to be attracted to the plastic surface. Thus, dust particles generated during the sawing operation are attracted to the plastic window due to the window maintaining an electrostatic charge. As is apparent, this static-induced dust contamination of the transparent window results in the operator not being able to see the blade as it passes through the workpiece, thus preventing the window from being effective. An additional problem associated with plastic windows is the fact that they are more susceptible to being scratched if the window is wiped clean of dust particles. More specifically, attempting to wipe the window of dust particles with a cloth will result in the dust particles digging into the soft plastic material, thus resulting in marring and scratching of the window. This marring and scratching, again, will obstruct the operator's view of the saw blade through the window. Therefore, a window construction is needed which will reduce the problem of static-induced dust contamination and, further, which will be resistant to scratching during a manual cleaning operation of the window.